How thin is the tread center by the time the wear indicators are flush? Do you usually wait until the indicators are flush to change your tires?

I've got over 4450 miles on my front tire and 2150 on the rear. There's still a bit of the wear indicators left (about the same front and rear). I don't want to be stupid, especially about the front, but I don't want to change the tires when there's still a lot of life in them, either. At the rate they're wearing I should have another 500 miles on the front, maybe 200 rear.

Any input???



ETA: I'll probably change them before CFC next weekend anyhow. But wondering if I ought to even change them before this weekend.